Form extension issue

When the SalesEditLines form is opened, I need to develop the SalesParmTable.Transdate to initialize to datenull(). (01/01/1900)

I developed using the eventhandler method of formdatasource. But it doesn't work properly.

I don't know where to reset TransDate for SalesParmTable to today.

I developed to reset TransDate to DateNull() after SalesParmTable's SalesId is changed, but this doesn't work either.

class TYM_AR_SalesEditLinesFormEventHandler
{

/// <summary>
/// add by dwkim, 2021-04-18, invoice date null logic
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
[FormDataSourceEventHandler(formDataSourceStr(SalesEditLines, SalesParmTable), FormDataSourceEventType::InitValue)]
public static void SalesParmTable_OnInitValue(FormDataSource sender, FormDataSourceEventArgs e)
{
SalesParmTable tSalesParmTable = sender.cursor();

;

info("111");
tSalesParmTable.Transdate = dateNull();
info(strFmt("%1", tSalesParmTable.Transdate));
tSalesParmTable.editFixedDueDate(true, tSalesParmTable.Transdate);
warning(strFmt("%1", tSalesParmTable.Transdate));

}

/// <summary>
/// add by dwkim, 2021-04-18, Invoice date mandatory
/// </summary>
/// <param name="args"></param>
[PostHandlerFor(formStr(SalesEditLines), formMethodStr(SalesEditLines, init))]
public static void SalesEditLines_Post_init(XppPrePostArgs args)
{
xFormRun xFr = args.getThis();
FormDataSource SalesParmTableDS = xFr.dataSource(formdatasourcestr(SalesEditLines, SalesParmTable));

// SalesParmTableDS.object(fieldNum(SalesParmTable, Transdate)).mandatory(true);

}

/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
[FormDataFieldEventHandler(formDataFieldStr(SalesEditLines, SalesParmTable, SalesId), FormDataFieldEventType::Modified)]
public static void SalesId_OnModified(FormDataObject sender, FormDataFieldEventArgs e)
{

FormDataSource SalesParmTable_ds = sender.datasource();
SalesParmTable tSalesParmTable = SalesParmTable_ds.cursor();

;

info("222");
tSalesParmTable.Transdate = dateNull();
info(strFmt("%1", tSalesParmTable.Transdate));
tSalesParmTable.editFixedDueDate(true, tSalesParmTable.Transdate);
warning(strFmt("%1", tSalesParmTable.Transdate));
}

/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
[FormDataFieldEventHandler(formDataFieldStr(SalesEditLines, SalesParmTable, Transdate), FormDataFieldEventType::Validated)]
public static void Transdate_OnValidated(FormDataObject sender, FormDataFieldEventArgs e)
{
FormDataSource SalesParmTable_ds = sender.datasource();
SalesParmTable tSalesParmTable = SalesParmTable_ds.cursor();

;

info("333");
tSalesParmTable.Transdate = dateNull();
info(strFmt("%1", tSalesParmTable.Transdate));
tSalesParmTable.editFixedDueDate(true, tSalesParmTable.Transdate);
warning(strFmt("%1", tSalesParmTable.Transdate));
}

/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
[FormDataFieldEventHandler(formDataFieldStr(SalesEditLines, SalesParmTable, Transdate), FormDataFieldEventType::Validating)]
public static void Transdate_OnValidating(FormDataObject sender, FormDataFieldEventArgs e)
{
FormDataSource SalesParmTable_ds = sender.datasource();
SalesParmTable tSalesParmTable = SalesParmTable_ds.cursor();

;

info("777");
tSalesParmTable.Transdate = dateNull();
info(strFmt("%1", tSalesParmTable.Transdate));
tSalesParmTable.editFixedDueDate(true, tSalesParmTable.Transdate);
warning(strFmt("%1", tSalesParmTable.Transdate));
}

/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
[FormDataSourceEventHandler(formDataSourceStr(SalesEditLines, SalesParmTable), FormDataSourceEventType::Created)]
public static void SalesParmTable_OnCreated(FormDataSource sender, FormDataSourceEventArgs e)
{
SalesParmTable tSalesParmTable = sender.cursor();

tSalesParmTable.Transdate = dateNull();

}

}